Can I tour on a fold up bike?

Cycling in Canada / US,
easier to carry on buses / trains - sounds great but can you ride one over large distances - 50km+ a day for 3 months?

What's the best bike to buy for touring?
I know I'll get what I pay for but how much
(at least )will it cost?

No valid reason why not, purpose made folding tourers are as light as conventional touring bikes, can have as many gears as you want to fit, and can be ridden just as fast, and there are a few that are almost indistinguishable from a standard machine (check the first link below) it's a matter of choice, make up your own mind, see details at
http://www.sandsmachine.com
http://www.foldabikes.com/panel/map.html
http://www.transalt.org/resources/foldin...
http://www.whycycle.co.uk/folders.html
http://www.breezerbikescom/bikes.cfm
http://www.bikesfriday.com/node/1666
Another point in their favour, they fold up into a case much smaller than a conventional bike, which makes it a lot easier
to stow if you are travelling by vehicle or plane.

You will need to unfold it first.

You would be far better off with a proper touring bike for comfort. The fold up bikes are really for convenience and not for long distances.

In theory you could, but I wouldn't recommend it. They are slower, heavier, less comfortable and more likely to break. It would make those long hauls very hard work.

When I trek I use a light, steel framed mountain bike (Marin) Why Steel? If the frame does crack just find the local welder and your away again! Good luck!

I wouldn't tour on a folding bike -- that doesn't mean it hasn't been done, albeit by few.

A folding bike doesn't give you optimum riding position for comfort or distance. Buy a touring bike if you are planning on spending 3 months in the saddle. Your touring will be a much more pleasant experience.

touring will require a large range of gears, which most modern folding bikes doesn't have. I think my Mum's has 3...

Also they're heavy and have tiny wheels, meaning it's less efficient.

You can take bikes on most trains nowadays, they usually have a special compartment for them. Look for a lightweight Steel framed bike - make sure the riding position is comfortable as you'll be on it for a while and get a nice strong leather saddle.

Also a steel frame would be able to accommodate panniers

edit - Just found an awesome link:
http://www.sheldonbrown.com/euhansen.htm...

HELL no. Fold up bikes are the weakest bikes ever created(from what i saw). after riding 50km+ for 5 days straight is gonna fall apart like a stack of dominoes lol. If you're going to do something like that getting a Road bike or a MTB.